Over the years skid steer loaders have been known as agile, compact vehicles with a high degree of maneuverability and a wide range of applications in the agricultural, industrial and construction fields. These vehicles usually include an engine, a boom assembly and an operators compartment mounted on a frame supported by four ground supporting wheels. Coupled to the engine are a main drive system and a lift system for the boom assembly. The vehicle is maneuvered by driving the wheels on one side at a different speed and/or in a different direction from those on the other side resulting in a turning motion, the severity of which is determined by the relative speeds.
Typically the engine, which is rear mounted for counterbalancing effect, drives a pair of hydrostatic pumps coupled to left and right mounted hydrostatic motors. Wheels on the left and right sides of the vehicle are driven by the left and right mounted motors through gears, chains and sprockets. Typically, motion is controlled by an operator seated within the operators compartment by actuating a pair of control levers which are linked to the pumps. The extent to which each lever is moved in a forward direction from a neutral position controls the amount of fluid supplied in a forward direction to its respective motor, and therefore the speed at which the wheels on that side of the vehicle will rotate. Similarly, the extent to which a lever is moved in the reverse direction from the neutral position will control the speed at which the associated wheels rotate in the reverse direction.
As mentioned above, skid steer loaders include a boom assembly. This assembly generally comprises a pair of lift arms pivotally mounted to the main frame, or a support frame extending upwardly from the main frame as shown in U.S. Pat. No. 5,042,602, issued Aug. 27, 1991 in the name of Toshinori Nakatani, et al. Attachments are usually mounted to the front of the lift arms.
A separate hydraulic system is used to actuate the boom assembly via hydraulic lift cylinders which drive the lift arms. This system is also used to actuate one or two tilt cylinders which pivot the attachment with respect to the lift arms. Typically, a pair of foot pedals in the front of the operator compartment control the flow of hydraulic fluid from an implement pump to the lift and tilt cylinders.
In addition to material handling buckets, various other attachments such as snow blowers, trenchers, tree spades and augers which include their own hydraulic motors are commonly mounted to the boom assembly. An auxiliary hydraulic system is used to control the flow of hydraulic fluid between the implement pump and the hydraulic motor of the front mounted attachment. It is common in prior art systems for the flow of hydraulic fluid to the motor to be controlled by an auxiliary spool valve through actuation of a handle on one of the control levers. The handle is normally biased to a neutral position. Pushing the handle in one direction strokes the auxiliary valve in a first direction, thereby causing hydraulic fluid to flow to the front mounted attachment in a first direction. Pushing the handle in the opposite direction strokes the auxiliary valve so as to supply fluid in a reverse direction.
There is a need in skid steer loaders, as in any vehicle, for convenient access to the transmission compartment, the engine, various drive components, etc., for servicing and repair. However, the compactness of skid steer loaders along with the inherent obstructions to access caused by the boom and boom mounting structure have given rise to unique problems that heretofore have not been satisfactorily addressed. For example, it is commonly practiced in vehicles such as trucks and tractors to pivotally mount the cab on the chassis but this does not embrace the problem of access to a vehicle such as a skid steer loader which by its nature includes structure not existing on conventional tractors. U.S. Pat. No. 4,116,484, issued Sep. 26, 1978 in the name of Vernon W. Mangless is illustrative of a tiltable tractor cab.
Also disclosed in the prior art is the general concept of providing a tiltable cab on a skid steer loader. In this regard, U.S. Pat. No. 4,401,179, issued Aug. 30, 1983 in the name of Robert M. Anderson, No. 5,042,602, issued Aug. 27, 1991 in the name of Toshinori Nakatani, et al, and U.S. Pat. No. 4,811,983, issued Mar. 14, 1989 in the name of Verne C. Watts, et al all show skid steer loaders with tiltable cabs and stationary boom supports on which boom arms are mounted.
It is also known in the prior art to provide skid steer loaders with means for moving the operators cab via non pivoting means. For example in the loader shown in U.S. Pat. No. 4,682,666, issued Jul. 28, 1987 in the name of Maurice Klee, et al, the cab is horizontally translatable.
In all known prior art apparatus of which applicants are aware there is no simple, convenient system for gaining access to the drive and transmission components. Even in those cases where skid steer loader cabs are pivoted or moved away from the frame there still exists other cumbersome obstructions such as the boom arms and the boom arm mounting structure in the form of an adjacent upright frame assembly. These obstructions have been contended with by either accepting their unwanted presence and working around them or in some instances they are removed prior to service and maintenance tasks, which removal is obviously an arduous and time consuming undertaking.